"I am very happy to be part of this great club," Lacroix said in a statement.
The transfer fee is said to be 670 million kronor, and the contract runs until 2032.
“The ambition is to lift trophies, and I look forward to contributing,” Lacroix continued.
The centre-back made three appearances for France during this summer's World Cup.
Lacroix previously played for Wolfsburg, before joining Crystal Palace in the summer of 2024. There he made 98 appearances and won three titles - the Conference League, the FA Cup and the Community Shield.
